1. Field of the Invention
The present invention relates to a parking brake device in which operation of a brake operation element is transmitted to a brake device via an operation cable and a booster mechanism.
2. Description of the Related Art
In a parking brake device of an automobile, operation of a brake operation element such as a parking brake pedal is transmitted to a brake device provided at a vehicle's wheels via an operation cable, and in this process, the operating force of the brake operation element is boosted by a booster mechanism before being transmitted to the brake device. The booster mechanism disclosed in Japanese Patent Application Laid-open No. 1-289750 comprises an intermediate lever with one end pivotally supported at a vehicle body, the other end thereof connected to the brake operation element via a front cable, and an intermediate portion thereof connected to the brake device via a connection cable, an equalizer and a rear cable. Accordingly, when the front cable is pulled by operating the brake operation element, the intermediate lever swings, and the movement of the intermediate lever actuates the brake device via the connection cable, the equalizer and the rear cable. At this time, the ratio of the distance from the fulcrum of the intermediate lever to the connection point of the front cable to the distance from the fulcrum of the intermediate lever to the connection point of the connection cable, namely, the lever ratio of the intermediate lever, becomes the boost ratio of the booster mechanism.
The above-described conventional brake device has the problem that when a large boost ratio of the booster mechanism is to be secured, it is necessary to set the lever ratio of the intermediate lever to be large, and therefore, the intermediate lever increases in size which increases the space required for layout.